Alastair Campbell always said his notorious comment "we don't do God" was misinterpreted.

His objection to a US reporter, at the end of an interview with Tony Blair was, he claims, born more out of frustration than any underlying strategy, as the journalist ventured his 11th "one last question".

The phrase, however, resonated, and all the more so when Mr Blair was open about his conversion to Catholicism after leaving office. The former prime minister also revealed the shock which had greeted his intention to end one speech with the phrase "God bless Britain". A fierce debate involving advisers and civil servants resulted and the idea was rejected. So whether it was inadvertent, as he likes to make out, Campbell's God "ban" struck a cord.

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The unease it suggests about mixing politics and religion is clear in David Cameron's article published in the Church Times this week about the importance of Christianity to him personally, and to the UK.

The article was insipid and hesitant, remarkable for the extent to which any statement the Conservative Prime Minister made was immediately qualified. As a Christian country, we should be more confident and evangelical, he said, rushing to add: "This does not somehow involve doing down other faiths." Christian values include "responsibility, hard work, charity, compassion, humility and love..." Mr Cameron asserted, but the sense is that the words tumbled out only so he could get on to the next bit where he conceded those values are shared by people of other faiths and none.

Those who advocate secular neutrality miss "the role faith can have in helping people to have a moral code", he began confidently at one point. But he was still hedging: "Of course faith is neither necessary nor sufficient for morality."

This all may be symptomatic of the conflict politicians feel in wading into this area. But it also means the piece will have pleased neither the faithful nor the secular, with its mealy-mouthed fence-sitting.

Why didn't he adopt the Campbell code? Timed ahead of Easter, his reassertion of his faith has been seen by observers as an attempt to build bridges with Anglican critics of policies such as welfare reform. Or it may be an attempt to reach out to middle-English church-going Tories, to stave off drift towards Ukip, perhaps.

Certainly, the Coalition government has vocal critics in the Christian churches. Their disquiet has been made obvious in open letters signed by dozens of Anglican bishops and other faith leaders. Religious and secular critics of the Government will find Mr Cameron's description of a "faith that compels us to get out there and make a difference to people's lives," hard to swallow.

The Tory view that encouraging people back to work is the best way to help them is sincerely held, but this is a Government which is making a difference to people's lives by hitting the vulnerable with the bedroom tax, and by cutting people off without an income for often questionable breaches of their job-seekers' agreements. It is the volunteers who man our food banks who make a difference to people's lives, many will feel, while the Government's contribution tends towards the negative. For all that the Church of England is traditionally "the Tory party at prayer", others feel Christian values such as loving thy neighbour are better reflected elsewhere on the political spectrum.

"Some people feel that in this ever more secular age we shouldn't talk about these things," Mr Cameron said. Which people?

We certainly should talk about them, because it is important to know what drives politicians. Religious views, sincerely held, might win over some and alienate others. But I would rather know about a politician's faith - far more than I care to know about their private life, for example.

That makes it all the more odd that religion has so far played so little part in the independence referendum debate. Catholics are the religious group most likely to vote Yes, according to a story published in this paper. The Kirk meanwhile has said it will not take a public view on the outcome it prefers. And otherwise, it is as if faith doesn't matter. But what motivates our leaders does matter. Most Scots, 54% according to the Scottish Social Attitudes Survey, claim to be of no religion. We don't do God. That doesn't mean our politics shouldn't.